High-normal A1c Signals CAD Risk in Nondiabetic Patients

Among patients who don’t have diabetes, high-normal HbA1c levels (at or above 5.8%) are strongly correlated with the risk of coronary artery disease….

In what they described as the first large-scale study to assess the relationships among HbA1c, CAD, and carotid intima-medial thickness, researchers enrolled 1,703 consecutive patients undergoing either elective or urgent coronary angiography at a single medical center during a 5-year period. These nondiabetic patients were divided into tertiles according to their HbA1c levels: low (less than 5.5%), intermediate (5.5%-5.79%), or high (5.8% or higher), reported Dr. Monica Verdoia of the cardiology department, Maggiore della Carita Hospital, Novara (Italy), and her associates.

HbA1c was significantly associated in a dose-dependent fashion with the prevalence of CAD on angiography (odds ratio, 1.33). CAD prevalence was 66.9% in patients who had low-normal HbA1c, 73.7% in those with intermediate HbA1c, and 78.6% in those with high-normal HbA1c. This association remained robust after the data were adjusted to account for many confounding factors, including patient age and sex; the presence or absence of hypertension, hypercholesterolemia, renal failure, and previous myocardial infarction; and the use or nonuse of medications including angiotensin receptor blockers, beta-blockers, nitrates, statins, or diuretics, the investigators said.

This strong association between high-normal HbA1c and CAD prevalence persisted across every high-risk subgroup that was assessed. HbA1c also was independently and strongly associated with carotid intima-medial thickness and the prevalence of carotid plaques on ultrasonography.

The best cutoff value for predicting the presence of significant CAD was determined to be 5.8%. Even though this level is within the normal range, it "should be regarded as a risk factor for atherosclerosis," Dr. Verdoia and her associates said.

Further research is needed to confirm these findings and to assess whether more aggressive preventive strategies, such as lifestyle changes, the use of statins, or antiplatelet therapies, might reduce the development and progression of atherosclerosis in such patients, they added.

Practice Pearls:

The prevalence of CAD was 66.9% in nondiabetic patients who had low-normal HbA1c, 73.7% in those with intermediate HbA1c, and 78.6% in those with high-normal HbA1c.

A1c levels (at or above 5.8%) are strongly correlated with the risk of coronary artery disease